WASHINGTON — The House of Representatives is expected to transmit articles of impeachment against Donald Trump to the Senate on Wednesday, setting the stage for a trial next week that will decide whether the 45th US president is forced from office.

After a weeks-long standoff over rules and witnesses, House Speaker Nancy Pelosi and Senate Majority Leader Mitch McConnell announced on Tuesday that what will be only the third presidential impeachment trial was now ready to move forward.

Pelosi is expected to sign the articles of impeachment at around 5:00 p.m. (2200 GMT) before they are then ceremoniously transferred from the House and travel through the US capitol's main hallways before being delivered to the Secretary of the Senate.

That ceremony will follow an announcement by Pelosi on which Democratic lawmakers will lead the prosecution case against Trump in the Senate, expected to begin next Tuesday.

Trump was impeached in December by the Democrat-controlled House on charges of abuse of power and obstruction of Congress.

But his conviction in the Senate is highly unlikely as the president's Republican Party has a 53-47 majority. A two-thirds majority to approve his guilt is needed if he is to be removed from office at the end of a trial expected to last two weeks.

Although the trial itself is unlikely to start until next week, Supreme Court Chief Justice John Roberts could be sworn in to preside over the process on either Thursday or Friday.

Trump has consistently painted the charges against him as part of a witch-hunt and again took to Twitter on Tuesday evening to decry his impeachment in the House as "the most lopsided & unfair basement hearing in the history of Congress!"

"While we're creating jobs and killing terrorists, Democrats in Congress are wasting America's time with demented hoaxes and crazy witch hunts," he told supporters at a rally in Winconsin.

At times, he has called the whole process to be stopped in its tracks while on other occasions he has apparently relished the prospect of turning the tables against his tormentors in a chamber where his supporters are in the majority.

McConnell pushed back on Tuesday against any suggestions that he would try and prevent the trial from going ahead.

"There's little or no sentiment for a motion to dismiss. We have an obligation to listen to the arguments," he added.

Pelosi meanwhile called for a fair trial and demanded the Senate subpoena witnesses and documents from the White House that will be crucial in the trial.

"The American people deserve the truth, and the Constitution demands a trial ... The president and the senators will be held accountable," she added.

Pelosi attacked suggestions by Trump and some of his supporters that the Senate, as soon as the trial opens, vote to dismiss the charges. That would only require a majority vote.

"A dismissal is a cover-up," she charged.

Trump was impeached on Dec. 18 when the House voted to formally charge him with abusing his power by illicitly seeking help from Ukraine for his reelection campaign.

He is accused of holding up aid to Ukraine to pressure Kiev to investigate former vice president Joe Biden, the front-runner in the race for the Democratic party's 2020 presidential nomination.

Trump is also charged with obstruction for holding back witnesses and documents from the House impeachment investigation in defiance of Congressional subpoenas.

The White House is steeling itself for a trial that could present damaging evidence against the US leader on national television.

Pelosi had delayed delivering the articles of impeachment to pressure the Senate to agree to subpoena witnesses with direct knowledge of Trump's Ukraine actions, including his chief of staff Mick Mulvaney and former national security advisor John Bolton.

McConnell said that, as with the impeachment trial of president Bill Clinton in 1999, the witness issue will only be considered after the 100 senators — the jurors in the trial — hear the prosecution and defense arguments.